Nyall Dawson ae00eb965c [FEATURE] Allow expression functions to use named parameters ...

This commit sets the framework for allowing expression functions to
use named parameters. Ie, instead of:

clamp(1,2,3)

you can use:

clamp( min:=1, value:=2, max:=3)

This also allows arguments to be switched, eg:

clamp( value:=2, max:=3, min:=1)

Additionally, it allows for a more structured definition of function
parameters to handle optional arguments and default values for
parameters. These are currently being done using a hacky infinite
argument list.

I've utilised the postgres ':=' syntax for specifying named arguments
to avoid potential collisions which may arise with the equality test
if we re-used just the '=' operator alone.

Sponsored by North Road

2016-04-04 13:59:13 +10:00

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[FEATURE] Allow expression functions to use named parameters

2016-04-04 13:59:13 +10:00